1. Field of the Disclosure
The present disclosure relates to a semiconductor light emitting device and a method of manufacturing the same, and more particularly, to a semiconductor light emitting device composed of a plurality of light emitting cells and a reflection film, and a method of manufacturing the same.
2. Description of the Related Art
Light emitting diodes (LEDs) are widely used as a means for transmitting, recording, or reading data in communication devices, such as optical communication devices, or in electronic devices, such as compact disc players (CDPs) and digital versatile disc players (DVDPs). The LEDs are expanding in applications to large outdoor sign boards, LCD backlights, and illumination devices.
Conventional semiconductor light emitting devices have used a sapphire substrate. The sapphire substrate can readily grow GaN light emitting cells with a thickness of 5 μm or more. However, the sapphire substrate is expensive and the manufacturing size is limited. Therefore, attempts to form large, inexpensive GaN light emitting cells on a silicon substrate have been made.
The light emitting diode having the GaN light emitting cells grown on a silicon substrate has a drawback in that there is a high possibility of cracks forming in the GaN light emitting cells due to the differences in the lattice constant and thermal expansion coefficient between the GaN light emitting cells and the silicon. The thickness of the GaN light emitting cells grown on the silicon substrate is generally limited to less than 1.0 μm to avoid cracking. However, when the GaN light emitting cells are too thin, their driving voltage becomes too high.
FIG. 1 illustrates an example of a matrix type display having a plurality of light emitting cells arranged in an array on a silicon substrate.
Referring to FIG. 1, a plurality of GaN semiconductor light emitting cells 120 are disposed on one silicon substrate 110, and each of the GaN semiconductor light emitting cells 120 forms a light emitting source. A desired image can be displayed on one substrate 110 by driving all the GaN semiconductor light emitting cells 120. Each of the GaN semiconductor light emitting cells 120 has a rectangular shape and the longer side of the rectangle is approximately 100 μm. The distance between the adjacent GaN semiconductor light emitting cells 120 is approximately 10 μm.
A conventional display having an array of the above GaN semiconductor light emitting cells 120 has a structure in which a low temperature nitride aluminum (LT-AlN) buffer layer is formed on the silicon substrate and a GaN semiconductor material layer is formed on the LT-AlN buffer layer. The structure can reduce defects and cracks of a GaN semiconductor material layer since the structure reduces residual stresses in the GaN semiconductor material layer. However, the structure requires a complex manufacturing process and, particularly, has a low optical output.